The overall goals of this project are to assess the impact radiologic technologists have on the accuracy and outcomes of mammograms in community practice, the mix of radiologic technologist characteristics in community practice, and the relationship between radiologic technologists individual characteristics and the interpretation of the mammograms they perform. With data on more that 1,800,000 mammograms for 575,000 individuals from 69 different radiology facilities over time, the Carolina Mammography Registry (CMR) is in a unique position to conduct this research. CMR data includes demographic information, individual health history, family health history, breast cancer risk factors, mammographic findings and assessments, recommendations for follow up care, pathology findings, and cancer outcomes. CMR records also include information on the technologist and radiologist responsible for each mammogram. We have longstanding collaborative relationships with radiology practices throughout the state of North Carolina, which will allow us to collect accurate and complete data on radiologic technologists characteristics using a survey instrument to be developed as a part of this project. Over the next four years we will: 1) Use existing CMR data to determine whether performance characteristics of screening and diagnostic mammography vary by technologist, (for screen-film and digital) from all facilities; and for technologists currently practicing in 48 facilities 2) Develop and implement a survey to collect data on technologist characteristics for a statewide sample of technologists; 3) Describe the variability of technologist characteristics; 4) Estimate the effect of technologist on the performance of screening and diagnostic mammography. This project will expand our understanding of the variability in radiologists final interpretations and recommendations. This work is novel. As technologists training and method of working with their radiologists is something that can be altered, the impact of this work could be extremely important, leading to improvement in screening outcomes.